Side-dependent effects of internal versus external Na and K on ouabain binding to reconstituted human red blood cell ghosts
Side-dependent effects of internal versus external Na and K on ouabain binding to reconstituted human red blood cell ghosts
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内部与外部 Na 和 K 对哇巴因与重组人红细胞血影结合的副作用
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
J. Hoffman
中科院分区：
文献类型：
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作者：
H. Bodemann;J. Hoffman
利用重组人红细胞血影评价了内部和外部Na和K对哇巴因结合率的副作用，如内部MgATP所促进的。这样的重影系统提供了[Na]i、[K]i、[Na]o和[K]o各自可以在其他物质不存在或固定在恒定浓度的条件下变化的情况。结果发现，在Ko存在下，增加[Na]i或[K]i导致哇巴因结合速率降低。[Na]i或[K]i的变化在没有Ko的情况下对哇巴因结合率没有影响。因此，哇巴因结合率被发现与Na：K和K：K交换率成反比，但与Na：Na交换率无关。Ko在拮抗哇巴因结合中的作用，以及Nao对这种相互作用的影响，被发现需要Nai或Ki的存在。解释的结果在一个模型有关的哇巴因结合位点的泵复杂的不同构象状态的可用性。与微粒体制剂相比，观察到红细胞血影的哇巴因结合特性存在差异，但尚不清楚差异的基础是否在于研究的不同制剂或微粒体系统中缺乏对侧性的控制。
The side-dependent effects of internal and external Na and K on the ouabain binding rate, as promoted by inside MgATP, has been evaluated utilizing reconstituted human red blood cell ghosts. Such ghost systems provide the situation where [Na]i, [K]i, [Na]o, and [K]o can each be varied under conditions in which the others are either absent or fixed at constant concentrations. It was found that, in the presence of Ko, increasing either [Na]i or [K]i resulted in decreasing the rate at which ouabain was bound. Changes in [Na]i or [K]i in the absence of Ko were without effect on the ouabain binding rate. Thus, the ouabain binding rate was found to vary inversely with the rate of Na:K and K:K exchange but was independent of the rate of Na:Na exchange. The effect of Ko in antagonizing ouabain binding, as well as the influence of Nao on this interaction, were found to require the presence of either Nai or Ki. The results are interpreted in terms of a model relating the availability of the ouabain binding site to different conformational states of the pump complex. Differences were observed in the ouabain binding properties of red cell ghosts compared to microsomal preparations but it is not known whether the basis for the differences resides in the different preparations studied or in the lack of control of sidedness in the microsomal systems.